U.S. swimming juggernaut Michael Phelps is looking forward to a lot more time with his family and on the golf course after he announced his retirement from professional swimming Monday.

Phelps, the most decorated Olympian in history with a total of 23 Olympic gold medals, said he is happy with his legacy following the 2016 Rio games and would like to leave the sport after the “greatest Olympics” he’s experienced.

"I am happy now and I think that is the biggest difference between now and 2012. In 2012 I just wanted to be done, I wanted nothing to do with the sport anymore and now I am very happy, very pleased with the place that I am in and I am happy with how I have finished my career," he said.

Phelps will leave Rio with five gold medals and a silver. Following his departure from swimming, the 31-year-old Phelps plans to marry his girlfriend, Nicole Johnson and spend more time with his son, Boomer.

"I'm pumped to golf, it's been a while since I have golfed,” he said. “I'm looking forward to that and just to relax, go hang with the pups, sit out back, get some sun and just hang."

United States' Michael Phelps reacts after the men's 100-meter butterfly final during the swimming competitions at the 2016 Summer Olympics, Friday, Aug. 12, 2016, in Rio de Janeiro, Brazil.

Russia's Evgeny Tishchenko won the Olympic heavyweight boxing gold medal, defeating Kazakhstan's Vassiliy Levit in a match so close that spectators booed the judges' unanimous decision.

Levit appeared to control much of the fight, but the three judges all gave Tishchenko the win in a score of 29-28.

In the track cycling men's omnium, Italy's Elia Viviani looked as though he would be out of contention for a medal following a mid-race crash, but he came back to win gold, finishing in Rio's Olympic velodrome.

Monday's competition also saw more gymnastic events.

U.S. gymnast Simone Biles wobbled on the balance beam, preventing her from reaching a goal to become the first female gymnast to win five gold medals in a single Olympics. Biles took bronze in the event and goes for her fourth gold Tuesday in the floor routine. Sanne Wevers of the Netherlands took gold on the balance beam and Laurie Hernandez of the United States won silver.

In men's gymnastics, Ri Se Gwang of North Korea took gold in men's vault and Eleftherios Petrounias of Greece won gold on still rings.

In the Greco-Roman wresting 130kg title, Mijain Lopez Nunez won Cuba's second gold medal of the 2016 Olympics as he beat Turkey's Riza Kayaalp.

World champion American runner Allyson Felix was blocked from earning her record fifth Olympic gold medal late Monday in the women's 400-meter final after Shaunae Miller of the Bahamas dove across the finish line and narrowly edged out Felix.

Felix ended the race with a time of 49:51, just shy of Miller's 49:44, to earn the silver medal. Miller took the gold while Jamaica's Shericka Jackson got bronze.

David Rushida of Kenya won the gold medal in the 800 meter race -- his second in a row -- in exciting fashion, edging out his closest competitor by just a few tenths of a second. Taoufik Makhloufi took silver with a time of 1:42.61 and American Clayton Murphy brought home bronze with a time of 1:42.93.

The U.S. currently leads the medal count with 26 golds and a total of 75. Great Britain comes in second with 16 golds and a total of 41, while China takes third with 15 golds and 46 total.